1. Field of the Invention
The present invention relates to a securing fixture for a heat sink, and especially relates to a securing fixture made from a metallic winding wire for the purpose of fixedly holding the heat sink on a PC board. With which, cost of production and effect of convenient detaching and mounting can be achieved.
2. Description of the Prior Art
CPU's of desktop computers 1 mostly, as the one shown in FIG. 1, are inserted each in a connector 2 (PGA base), and then the connector 2 is fixedly connected to a PC board 3. The CPU 1 will get high temperature during operation, the top of it is provided with a heat sink 4, so that heat generated from the CPU 1 will be absorbed by the heat sink 4 before heat sinking.
The heat sink 4 is superimposed on the CPU 1 which is inserted in the connector 2, and has a height difference from that of the PC board 3. Thereby, when the heat sink 4 is fixed on the CPU 1, it can be engaged and locked on an edge of the CPU 1 with an engaging member 5 extending downwardly from an edge of the heat sink 4, or can be engaged and locked on the connector 2, to complete fixing of the heat sink 4.
The structure of the engaging member 5 as shown in FIG. 1 is very simple, it can be integrally formed by injection molding in the way of mass production without further processing. Hence it has the advantage of low cost. However, such engaging member 5 can only be applied to the CPU 1 being inserted in the connector 2, and thereby has a height difference from the PC board 3; it cannot be applied to a CPU 1 being directly connected with the PC board 3.
As shown in FIG. 2, a notebook type computer is designed primarily on account of saving space, and has an object of being light, thin and convenient for carrying. Therefore, most elements thereof are surface mounting devices (SMD), i.c. the CPU 1 is fixed on the PC board 3 by the surface mounting technique (SMT) to save space.
The structure directly having the CPU 1 fixed on the PC board 3 does not have a gap for engagement of the engaging member stated above by virtue that the CPU 1 is laid parallelly on the PC board 3. So that when the heat sink 4 is fixed on the CPU 1, the PC board 3 and the heat sink 4 must be excavated to form mutual corresponding engaging holes 61, 62 respectively to be engaged with engaging members 7. And the heat sink 4 can be superimposed on the top of the CPU 1 and is fixed on the PC board 3.
The structure of each of the engaging members 7 is shown in FIGS. 2 and 3, and is provided on the top thereof with a head 71, a spring 72 is slipped over the shank of the engaging member 7 which has a bottom end in the shape of an arrow with an engaging end 73 having a diameter larger than that of the corresponding engaging hole 61 (62). The engaging end 73 has an opening to permit elastic contracting and stretching of the engaging end 73. When in use, the head 71 is pressed down to move down the engaging end 73. When the engaging end 73 is moved to abut on the engaging hole 61 of the heat sink 4, it can be extended through the engaging hole 61 by virtue that the opening of the engaging end 73 is contracted. When the engaging end 73 is extended through the engaging holes 61, 62 respectively of the heat sink 4 and the PC board 3, the engaging end 73 is clastically stretched out to engage beneath the engaging hole 62 of the PC board 3. In this way, the heat sink 4 superimposed on the top of the CPU 1 can be fixed on the PC board 3 by means of the engaging members 7. And the function of the springs 72 is to provide elastic action force to render the heat sink 4 tightly lapped over the top surface of the CPU 1 after the engaging members 7 are engaged onto the heat sink 4 and the PC board 3.
Each of the above stated engaging members 7 needs only a single pressing action to get its effect of convenient use when it is to be fixed on the heat sink 4, however, it still has the following defects:
1. When it is required to detach the heat sink 4, a pair of pincers are required to pinch the engaging end 73 for closing under the PC board 3 to reduce the diameter of the engaging end 73 and remove it. The bottom of the PC board 3 is in the lowest layer of the housing of the notebook type computer. Therefore, when it is required to detach the heat sink 4, the PC board 3 shall be detached firstly, this is troublesome and is a defect in detaching. PA1 2. When in manufacturing the engaging members 7, a die shall be built, and plastic is used for molding, further, springs 72 are slipped over the engaging members 7. Cost for building a die is expensive, and slipping over of the springs is time and money consuming, these all increase the cost of production. PA1 1. The securing fixtures are integrally made from winding metallic wires. It does not need to build an expensive die for manufacturing securing fixtures, nor the securing fixture needs additional processing, thereby the securing fixtures have the effect of saving cost. PA1 2. In detachment, it needs only to slightly push a side of a securing fixture to contract the limiting portion on the top of the insertion end by the linking-up relationship among the action rod section, the movable rod section and the PC board to release the insertion end from the engaging hole of the PC board. Such detachment is very convenient, and when in slightly pushing a side of the securing fixture, if the direction of the pushing force is wrong, the detachment cannot be effected. Hence no dropping due to inadvertent wrong action will occur.